Parameters optimization of supercritical fluid‐CO2 extracts of frankincense using response surface methodology and its pharmacodynamics effects

The volatile oil parts of frankincense (Boswellia carterii Birdw.) were extracted with supercritical carbon dioxide under constant pressure (15, 20, or 25 MPa) and fixed temperature (40, 50, or 60°C), given time (60, 90, or 120 min) aiming at the acquisition of enriched fractions containing octyl acetate, compounds of pharmaceutical interest. A mathematical model was created by Box‐Behnken design, a popular template for response surface methodology, for the extraction process. The response value was characterized by synthetical score, which comprised yields accounting for 20% and content of octyl acetate for 80%. The content of octyl acetate was determined by GC. The supercritical fluid extraction showed higher selectivity than conventional steam distillation. Supercritical fluid‐CO₂ for extracting frankincense under optimum condition was of great validity, which was also successfully verified by the pharmacological experiments.     

Efficient homocoupling reactions of halide compounds catalyzed by manganese (II) chloride

A new efficient homocoupling reaction was reported in one pot by a combination of metallic magnesium and a catalytic amount of manganese (II) chloride. Various aromatic and alkyl halides underwent homocoupling smoothly, affording the corresponding symmetrical homocoupling compounds in moderate to good yields. The readily available MnCl₂, the mild reaction conditions and the operational simplicity and practicability allow for an easy and practical procedure for the purpose of carbon carbon bond formation. Copyright © 2007 John Wiley & Sons, Ltd.     

Monolithic integration of electroabsorption modulator and DFB laser for 10-Gb/s transmission

A strained InGaAsP-InP multiple-quantum-well DFB laser monolithically integrated with electroabsorption modulator by ultra-low-pressure (22 mbar) selective-area-growth is presented. The integrated chip exhibits superior characteristics, such as low threshold current of 19 mA, single-mode operation around 1550 nm range with side-mode suppression ratio over 40 dB, and larger than 16 dB extinction ratio when coupled into a single-mode fiber. More than 10 GHz modulation bandwidth is also achieved. After packaged in a compact module, the device successfully performs 10-Gb/s NRZ transmission experiments through 53.3 km of standard fiber with 8.7 dB dynamic extinction ratio. A receiver sensitivity of −18.9 dBm at bit-error-rate of 10⁻¹⁰ is confirmed.     

A double wavelength DFB laser with an identical active area for CWDM

A novel distribute feedback (DFB) laser which gave two different wavelengths under two distinct work conditions was fabricated. The laser consists of two Bragg gratings with different periods corresponding to wavelength spacing of 20 nm in an identical active area. When driving current was injected into one of the different sections separately, two different wavelengths at 1542.4 and 1562.5 nm were realized. The side mode suppression ratio (SMSR) of 45 dB or more both for the two Bragg wavelengths were achieved. The fabricating process of the laser was just the same as that of traditional DFB laser diode. This device can be potentially used in coarse wavelength division multiplexer (CWDM) as a promising light source and the technology idea can be used to enlarge the transmission capacity in metro area network (MAN).     

DIRICHLET PROBLEM FOR THE IMPLICIT OBSTACLE PROBLEMS

In this paper the implicit obstac|e problem of fully nonlinear second-order elliptic equations associated with impulsive control problem are investigated. The comparlon principle for viscosity solutions is proved,the existence and uniqueness results are disscussed.     

Nd-Ti-V催化剂的制备及在均酐制备上的应用

采用喷涂法制备了钕改性的钒系／瓷球五元复合氧化物催化剂，实验表明：使用该催化剂，在反应温度４６０±１０℃、空速６０００～８０００ｈ－１、均四甲苯在空气中的浓度２０±３ｇ／ｍ３时，固体粗酐的收率９５％～１００％，产品的质量好，副产物少，易于精制提纯。该催化剂具有重现性好、稳定性高、使用寿命长的特点。     

二元等比锰硫MnnSn(n=1-7)团簇的结构与性质研究

采用密度泛函理论系统研究了二元等比锰硫团簇MnnSn(n=1-7)的结构和物理性质。首先得到了体系的最低能量结构以及相应的亚稳态同分异构体,讨论了团簇几何结构的生长模式和结构稳定性。通过电荷转移和差分密度分析发现Mn原子和S原子之间离子键和共价键的共存效应可以有效提高团簇结构稳定性。当原子数为奇数和偶数时,锰硫团簇的磁矩分别为5uB和淬灭状态,呈现出奇特的二元奇偶振荡现象,通过布局分析和态密度进一步探索了团簇磁性的来源和具体分布情况。